The air we breathe contains different individual gases (mostly nitrogen and oxygen). Which of the following correctly describes the air we breathe?


a

element

b

compound

c

mixture

d

none of these

Answer:

Go to your periodic table and look for each element. Find the mass for Aluminum, Nitrogen, Oxygen, and Hydrogen.

After you find those, for each compound you must add them together and find the least amount of sig figs after the decimal point.

For the first compound, Al(NO3)3, you will have a total of

1 Aluminum atom

3 Nitrogen atoms

9 Oxygen atoms

Aluminum has 26.982 g/mol

Nitrogen has 14.007 g/mol

Oxygen has 15.999 g/mol

Now multiply those numbers by the amount of atoms of each element.

(1)26.982 g/mol = 26.982 g/mol

(3)14.007 g/mol = 42.021 g/mol

(9)15.999 g/mol = 143.991 g/mol

now add all of those numbers together, and you see that their least significant figure after the decimal is 3, so round to 3 digits after the decimal point.

26.983 + 42.021 + 143.991 = 212.994

now do the same for the other compound

to start you off.. you have

6 Hydrogen atoms

3 Oxygen atoms

Hydrogen has 1.009 g/mol

Oxygen has 15.999 g/mol

the least significant figure after the decimal point is 3, so round you 3 digits after the decimal point.

after you finish getting your totals, you. until them and find the greatest sig fig over all. comment on this if you need further instruction :)

Answer:

SYMBOLS, FORMULAS AND MOLAR MASSES

OBJECTIVES

1. To correctly write and interpret chemical formulas

2. To calculate molecular weights from chemical formulas

3. To calculate moles from grams using chemical formulas

INTRODUCTION

Part I. Symbols and formulas

An element is a homogeneous pure substance made up of identical atoms. All matter is made

up of elements and, since chemistry is the study of matter, it is convenient to use symbols to represent

the elements rather than using the entire name.

By international agreement, specific symbols are assigned to each element (Note: This means

that while names of the elements vary with language, symbols are constant throughout the world.) Each

element is assigned a one- or two-letter symbol. The first letter is capitalized, the second (if there is

one) is not. While this often seems trivial, it is in fact a very important point. For example, in chemical

language Co represents cobalt, which is a metal and an element, while CO represents carbon monoxide,

a compound which is a colorless, odorless gas! Even when there is not an obvious correspondence,

for instance "MN", it can cause confusion. Do you mean the element manganese? Did you forget a

letter and mean something else? Are you using "M" to represent something else entirely? Chemists

sometimes use "M" to represent any metal. It is well worth the trouble to memorize the symbols for

common elements.

Since compounds consist of elements, the chemical formulas of compounds also consist of

elements with subscripts used to denote the number of atoms per molecule. If there is no subscript, it is

implied that there is one of that kind of atom. Ones never appear in chemical formulas. Not only do

subscripts denote ratios of atoms, they also denote the ratio of moles of element to one mole of

compound. Parentheses can be used to show groups of atoms, with the subscripts showing how many

groups there are. Parentheses are not used if there is only one group.

Examples: For one mole of the following compounds, how many moles of each element are

present?

MgCl2 1 mole Mg, 2 moles Cl

Mg(NO3)2 1 mole Mg, 2 moles N, 6 moles O

NaNO3 1 mole Na, 1 mole N, 3 mole O

AgCl 1 mole Ag, 1 mole ClPart II. Molar Masses

Each atom has a different size and therefore a different mass. The relative masses of each

element can be found on the periodic table. For example, one atom of magnesium weighs 24.31 amu

(atomic mass units). However, one mole of magnesium weighs 24.31 g. (Moles were planned that

way!) Since one mole of MgCl2 consists of one mole of magnesium and two moles of chlorine, the

mass of one mole of MgCl2 must be the sum of the masses of the elements. The mass of one mole of a

substance is called the molar mass or molecular weight.

Examples: What is the molar mass of the following compounds?

MgCl2 24.31 + 2(35.45) = 95.21 g/mol

Mg(NO3)2 24.31 + 2(14.01) + 6(16.00) = 148.33 g/mol

NaNO3 23.00 + 14.01 + 3(16.00) = 85.01 g/mol

AgCl 107.9 + 35.45 = 143.4 g/mol

(Note: Yes! You DO have to count significant figures when calculating molecular weight/molar

mass. However, the number of significant figures may vary depending on which periodic table you use.)

Chemists are generally interested in number of moles. Unfortunately, it is impossible to measure

moles directly. However, masses are easily measured, and if the chemical formula of the compound is

known, the molar mass can be used to determine the number of moles. The molar mass is defined as:

molar mass = grams/moles = g/mol (1)

Moles may be calculated by using molar mass as a conversion factor in dimensional analysis where

molar mass in grams = 1 (exactly) mole of compound (2)

This method is used in multi-step calculations. For example, if 0.873 g of MgCl2 is weighed out, it

is 9.17 x 10-3

moles.

1 mole

0.873g x 95.21 g = 9.17 x 10-3

mol MgCl2 (3)

However, 0.873 g of AgCl is only 6.09 x 10-3

mol.

1 mole

0.873g x 143.4 g = 6.09 x 10-3

mol AgCl (4)Molar mass may also be used to relate moles to grams. For example, 0.158 mol of MgCl2 is 15.2 g.

0.158 mol x 95.21 g = 15.2 g MgCl2 (5)

1 mol

Percent is used to express parts per one hundred. Usually in chemistry, it refers to

g of species of interest x 100 = % (6)

g of whole thing

Example: For the % Mg in MgCl2: In one mole of MgCl2, there are 24.31 g of Mg (molar mass of Mg,

the part we are interested in) and 95.21 g of MgCl2 (the whole thing), so %Mg in MgCl2 is

(24.31/95.21) x 100 = 25.53% Mg (7)

PROCEDURE

Work individually.

The formula for calcium phosphate is Ca3(PO4)2. Weigh about 2 g of calcium phosphate to the

nearest 0.001 g. In other words, you do not have to have exactly 2.000g, but you must know the

weight you have exactly. Acceptable results include but are not limited to: 1.985g , 2.035g, 2.314g

etc.

Be sure to report all results with the correct number of significant figures and appropriate units!

Answer:

number of moles =

[tex]53.3 \times 10 {}^{3} mol[/tex]

Explanation:

here's the solution in attachment.

Answer:

Natural Resource

Explanation:

A natrual resource is something that was created when Earth was first made. They were intended to fulfill human needs when they needed them. An example of a natural resource can be water, because we will need water to survive.

A. A poster that features brief sentences conveys urgency and simplifies content.

Answer:

Explanation:

c. - vaccine

b. - immunity

d. - phagocyte

f. - b cell

e. - t cells

a. active immunity

Answer:

D as a mixture is not a compound and it does not have it's own chemical formula

Explanation: Sauce me brainliest

It cannot be described by a chemical symbol or formula.

- Chilio

Answer: The kinetic energy of an object depends on both its mass and velocity, with its velocity playing a much greater role. Examples of Kinetic Energy: ... A baseball thrown by a pitcher, although having a small mass, can have a large amount of kinetic energy due to its fast velocity.

Explanation:

Hope this help

Answer:

Stem

Explanation:

Answer:

option-(d) stem

Explanation:

Stems have four main functions which are: Support for and the elevation of leaves, flowers and fruits. The stems keep the leaves in the light and provide a place for the plant to keep its flowers and fruits. Transport of fluids between the roots and the shoots in the xylem and phloem...

I hope it help you

Answer:

Humans

Explanation:

Humans have energy of motion and store energy.

Every object will have any form of energy. For instance, when we are walking we gains a kinetic energy. We use electronic devices where electrical energy is stored and can be converted to mechanical energy to activate any motors.

Energy can neither be created nor be destroyed. However it can be transformed to any other forms. Thus, the total energy will conserved always.

We have a lot of example for energy transformation and storage. The energy form stored by virtue of the position of an object is called potential energy. Whereas, when the object starts moving potential energy converts to kinetic energy.

Thus, thermal vibrations of particles, our every day activities all are associated with a kinetic energy. Kinetic energy  of each body depends on the mass and velocity of the body. The more the mass and velocity more will be the kinetic energy.

To find more on kinetic energy, refer here:

https://brainly.com/question/26472013

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Answer:

hope this helps!

Explanation:

This law states that a still object will stay still unless a force pushes or pulls it. A moving object will stay moving unless a force pushes or pulls it. Gravity and friction are forces that constantly push and pull the "stuff" on earth. So, when we roll a ball, it slowly comes to a stop.

Answer:

bytbyufvguv vvg uggy yvgu vgu gyu7yng8ugng88yn

Answer:

the answer is (G)

Explanation:

It is G!

Your welcome!

Answer: A. The oceans‘ tidal would be smaller because the moon would exert less gravitational pull on earths oceans.

Explanation:

i got it right :)

Answer:

Differences: Earth's atmosphere has 5 main layers where as atmospheric layers thins out in each higher layer.

Similarities: They both have multiple layers.

Explanation:

Sorry I only have 1 difference and similarity.

Answer:

9.5 m

Explanation:

First, divide 4.75 m by the 0.50 l

4.75/0.50

This leaves you with 9.5 m

Answer:

option c

Explanation:

as catalyst increases the reaction while activation energy is inversely proportional to rate of reaction, so option c is correct

The purpose of a catalyst to lower the activation energy of a reaction.

A type of chemical that, without becoming consumed by the process, speeding a chemical reaction or reduce the temperature as well as the pressure required to initiate one. The addition of a catalyst to speed up a reaction is known as catalysis.

The bare minimum additional energy needed by a reactive molecule to transform into a product is considered as activation energy.

The purpose of a catalyst is to lower the activation energy of a reaction.

Therefore, the correct answer will be an option (C).

To know more about catalyst and activation energy.

https://brainly.com/question/11334504

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Answer:

0,1276 M

Explanation:

Molair mass of NaOCl = 74,44 g/mol

You have 9,5 g/L.

You need to calculate with the molair mass, how many moles 9,5 g are:

9,5 g / 74,44 g/mol = 0,1276 mol

0,1276 mol / 1 L = 0,1276 M

The molarity of a bleach solution containing 9.5 g of NaOCL per liter of bleach is mathematically given as

M= 0.1276 M

Generally, the equation for the  Molar mass  is mathematically given as

M=m/(g/mol)

Therefore

M=9,5 g / 74,44 g/mol

M= 0,1276 mol

Hence

M= 0.1276 M

In conclusion, the molarity

M= 0.1276 M

Read more about  Molarity

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Answer:

Under normal conditions, a magnetic material like iron doesn't behave like a magnet because the domains don't have a preferred direction of alignment. On the other hand, the domains of a magnet (or a magnetized iron) are all aligned in s specific direction.

Explanation:

Answer:

Matter

Explanation:

All matter is made up of substances called elements

Answer:

Explanation:

Chapter 4: Energy from Combustion The primary means of generating energy for human

endeavors is the combustion of fuels.

Coal - burned in power plants

Gasoline - burned in automobiles

Natural gas - heating

Heating oil – heating

.Propane, charcoal, wood, candles, …

Combustion (burning in air) releases the chemical energy,stored in the chemical bonds of the fuels.  

BRAINLY PLZ

The vapor pressure (in torr) of a 35°C solution : 52 torr

Given

x propanol = 0.75

P°ethanol=100 torr

P°propanol=36 torr

Required

the vapor pressure

Solution

Raoult's Law

P solution = xA.P°A +xB.P°B

x ethanol = 1- 0.75 = 0.25

Input the value :

P solution = 0.25 x 100 + 0.75 x 36

P solution = 25 + 27

P solution = 52 torr